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DIY Slug-o-Tron: barrel slugging machine

Acknowledgements: big thank you to a lot of members on another forum: RKG, 50BMG, Slowdive and EddieCoyle on awesome insight and ideas for this little adventure, also to (<>) crew.

greeting comrades. Some time ago, never mind how long, I came across problem of slugging many barrels of most glorious Mosin rifle. It is true that you should slug your Mosin barrel as many vary anywhere mostly from .310 to .315. Thus, selecting ammo to fit rifle will provide you with accuracy. Sniper rifles were selected for two parameter: one is how straight the bore was, the other was how close it was to factory ammo (since no sniper ammo existed during WWII)

Before you hunt me down and cut my hands off, keep in mind:

1. These are not ... some of ... my barrels
2. I did not mutilate these most glorious rifles made in defense of motherland
3. They will all be restored to most awesome glory and fire many cartridge of ammo in future!

Anyway, many barrels, very long time to slug all. Thus I made this machine and call it "Slug-o-Tron" Basically, this machine could slug a barrel in 15 sec and provide more information on which I elaborate later.

Here is my original setup, it is a 110V wench that drags steel cable with slug attached to it.

To make slugs, I cut up a bunch of #8 bolts. You can probably make that from a threaded rod, but at my HD the rod was as expensive and I need to have good threads one end.

Before casting, I screw the threaded piece into a 1/4 brass rod:

The mold body is made from scrap aluminum and three drill bits. I drill 1/4 hole all the way through. Then start with 5/16 and round leading edges on another to finish drilling:

using the spacer under the mold, once soft lead is cast, I tap the top off, tap the mold on the ground and slug comes out like this

the slug is attached to the steel cable of wench like this:

now you know why #8 threaded rod is used. I use length of 3/16 steel brake line, it is perfect for cable and is perfect to tap #8 inner threads.

why is slug drugged by the wench? Because slugging from muzzle can give you one thou variation vs. slugging from the chamber.

in addition, I added a load cell to measure the tension on the cable continuously

some barrels are airgaged (French did first airgaging) and this can very accurately measure barrel internal diameter and also variations in caliber inside, flat spots etc. The theory is that when wench pulls boolit through barrel, tension will drop at the increased dia and tension will increase once boolit passes into a tight spot:

I slagged a couple of barrels and I could see that each barrel has its own, unique "signature" that is repeatable every time. Here are four graphs of slagging two barrels. You can see that each barrel has very unique pattern.

here are three more graphs of three other different barrels:

Since slugs are good for any rifle in the most glorious (7.62) caliber, I slugged several AKs:

Romy AK is f-up, I don't even remember what it slugged as, not very accurate at all. Arsenal is ok, it slugged at around .312 and shoots acceptable. Polish AK slugged at .309 and is very accurate despite flimsy collapsible stock.

I will post more pictures of the setup. I don't think that tension graph tells you something dramatic as to decisively determine accuracy of rifle, but it does corroborate the evidence of good shooting rifle. In short, there are many of factors to make rifle shoot well and bore is one of them.

Also, for people who lap their bores, tension graph may be useful to gage results of work.

The solid soft lead bullet is undoubtably the best and most satisfactory expanding bullet that has ever been designed. It invariably mushrooms perfectly, and never breaks up. With the metal base that is essential for velocities of 2000 f.s. and upwards to protect the naked base, these metal-based soft lead bullets are splendid.
John Taylor - "African Rifles and Cartridges"

Forget everything you know about loading jacketed bullets. This is a whole new ball game!

This demonstrates why we have the best website in the world, bar none!!!! Thanks Boris.
Ole Jack

"'Necesity' is the plea for every infringement of human freedom. It is the argument of Tyrants: it is the creed of slaves."
William Pitt, 1783"America will never be destroyed from the outside. If we faulter and lose our freedoms, it will be because we destroyed ourselves." Abraham Lincoln.

Seriously a strap winch off a truck trailer with a padded stop in front to stop the gun from moving towards it would easily drag a slug from breach to muzzle on an assembled rifle, and the whole thing could be assembled on a 4x4 with a padded cradle for the gun to rest in. clamp it in a vise and you are ready to go.

Also if you don't want to cut off screws you can buy a box of long 8/32 x 1" set screws for about $4.00 at any industrial bolt supplier.